In recent years, a recessed channel transistor (RCAT) in which the lower portion of the gate electrode is buried in the interior of a silicon substrate has been proposed as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) to increase the on-state current and downscale while suppressing the leak current between the source and the drain. In the RCAT as well, it is desirable to increase the on-state current even further.